The present invention is directed to a method and circuit arrangement for transmitting a continuous bit stream upon involvement of an ATM network.
A method for forwarding message cells, each of which having a cell header identifying the respective virtual connection and being transmitted on offering trunks during the course of virtual connections according to an asynchronous transfer method via cell switching equipment that has at least two redundant switching matrices to serving trunks connected thereto, is described in European Patent Application 89 10 3798. In this method, a message cell group having a plurality of identical message cells corresponding in number to the plurality of redundant switching matrices is formed by duplication for each of the message cells transmitted on one of the offering trunks during the course of a virtual connection. An identical auxiliary identifier that changes for successive message cell groups and has the form of a continuously assigned message cell sequence number is thereby entered in the cell header of each of the message cells of a message cell group. Subsequently, the message cells of a message cell group are separately transmitted via the redundant switching matrices in the direction of the relevant serving trunk for the respective virtual connection. Finally, after such a transmission over the redundant switching matrices only one of the message cells belonging to a message cell group is forwarded to the serving trunk. This message cell is forwarded on the basis of the auxiliary identifier respectively attached to the message cells.
Over and above this, a method for switching message cells of a transmission system that transports a message cell stream according to an asynchronous transfer method via a switching network constructed with modules is described in European Patent Application 91 10 7434 (corresponding to U.S. Ser. No. 880,188 filed May 5, 1992, now allowed, and hereby incorporated by reference). The transport bit rate of the transmission system amounts to a multiple of the transmission bit rate of the switching elements of the modules. Message cells to be switched are thereby distributed onto one of the switching network inputs corresponding in number to the multiple, being respectively distributed upon attachment of information. This information references all those modules over which the respective message cells are to be through-connected to an output of the switching network. The message cells transmitted to various outputs are then again combined to form a message cell stream. What is thereby provided, among other things, is that a cyclically continuous sequence number is attached in call-associated fashion to the message cells before the through-connection with the switching network, the sequence of the message cells for every connection being assured with reference to this sequence number in the combining to form the message cell stream. It is also provided that the message cells are cyclically distributed onto the switching network inputs.